Acrylic - BMI 777 Polymer-Modified Base Coat

Polymer Modified Base Coat

BMI 777 Polymer-Modified Base Coat is a high-performance, fiber-reinforced, dry mix, polymer modified, cementitious base coat specifically formulated for use with BMI Acrylic system.

Compliance with the following codes:

• 2009 International Building Code (IBC)
• 2009 International Residential Code (IRC)

Usage

BMI 777 Polymer-Modified Base Coat is used to embed reinforcing mesh as part of the base coat for BMI Acrylic systems. Appropriate substrates:

• Exterior fiber reinforced cement or calcium silicate
• boards
• Unglazed brick
• Cement plaster
• Concrete or masonry
• Galvanized expanded metal lath 2.5 or 3.4 lb/yd²

Advantages

Compliance with the following codes:

• 2009 International Building Code (IBC)
• 2009 International Residential Code (IRC)

Packaging

50 lb (22.7 kg) bag

Product Details

Sustainability / Certifications / Approvals

APPROVALS / STANDARDS

Testing:

• Surface Burning Characteristics - ASTM E-84
• Water Vapor Transmission - ASTM E-94 Procedure B
• Accelerated Weathering - ASTM G-23 (Carbon Arc)
• Freeze-Thaw Resistance - ASTM E-2485
• Water Resistance - ASTM D-2247
• Tensile Bond - ASTM C-297/E-2134
• Water Penetration - ASTM E-331
• Ignitability - NFPA 268

Product Information

Shelf Life

12 months from date of production if stored properly in original, unopened and undamaged sealed packaging

Storage Conditions

Store dry at 40-95 °F (4-35 °C)
Protect from moisture and weather. If damp, discard material

Application

Application Information

Layer Thickness

The minimum base coat thickness shall be sufficient to fully embed the BMI Mesh.

Waiting Time / Overcoating

~ 24 hours
As the temperature will affect the pot life, application temperature:

• Above 73 °F (23 °C) will reduce the pot life and workability
• Below 73 °F (23 °C) will extend the pot life and workability

Consumption

Coverage

120 ft² (11 m²) per bag

(Coverage figures do not include allowance for surface profile and porosity or material waste)

Application Steps

MIXING

Drill and paddle

• Add 5-6 quarts of clean potable water into a clean plastic container.
• Add BMI 777 Polymer-Modified Base Coat slowly while constantly mixing with a “twister” paddle or equivalent mixing blade, powered by a drive at 500-1200 rpm*.
• Thoroughly mix until uniformly wetted, adjusting consistency with a small amount of water or BMI 777 Polymer-Modified Base Coat.
• Allow the material to set for 3-5 minutes then retemper, adding a small amount of water if necessary.
• Material must be free of lumps before using.

Mortar mixer

• Add 5-6 quarts of clean potable water for each 50 pound bag of BMI 777 Polymer-Modified Base Coat.
• Add the BMI 777 Polymer-Modified Base Coat while the mixer is running.
• Let mix 3-5 minutes, then run mixer for another 2-3 minutes to break the set adding a small amount of water if necessary to adjust workability.
• The pot life is 1-1.5 hours depending on weather.

*A minimum 7 amp drill works best for Portland cement based materials.

APPLICATION

• All insulation board irregularities greater than 1/16" (1.6 mm) must be sanded flush.
• Apply BMI 777 Polymer-Modified Base Coat to the entire surface of the insulation board.
• Fully embed the BMI Mesh in the wet base coat troweling from the center to the edge of the reinforcing mesh so as to avoid wrinkles.
• The BMI Mesh shall be continuous at all corners and lapped or butted in accordance with BMI’s recommendations.
• Two coats applications is recommended.
• All areas requiring higher impact resistance shall be detailed on the plans and described in the contract documents.

• Temporary protection shall be provided at all times until the base coat, finish and installation of permanent flashings, sealants, etc. are completed to protect the wall from inclement weather and other sources of damage.

CURING TREATMENT

• Protect work from rain for at least 24 hours.
• Being a cementitious product, the BMI 777 Polymer-Modified Base Coat mixture develops full strength in 28 days.

CLEANING OF TOOLS

• Clean tools and equipment with water immediately after use while it is still wet.

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